A bookbinding adhesive has been widely used for bonding together sheets of paper and a book cover for use in bookbinding, and an EVA (ethylene-vinyl acetate copolymer) adhesive and a moisture-curing polyurethane hot-melt adhesive (RHM) are in the majority in the bookbinding adhesive.
However, the EVA adhesive which has been already known is required to be increased in the thickness of the applied adhesive film for exhibiting a satisfactory bond strength, and, as a result, a problem occurs in that the book obtained by bookbinding using the EVA adhesive has poor book opening properties.
On the other hand, with respect to the conventional moisture-curing polyurethane hot-melt adhesive, there are only those having a high viscosity such that the adhesive overflows an adhesive box or is scattered when it is applied at a high speed, and those having a low viscosity such that the adhesive is too hard, and any of them do not satisfy all the high-speed application properties, the cutting properties, and the book opening properties.